QUESTIONS: THORAX

During transesophageal echocardiography (TEE), an ultrasound transducer is placed through the nose or mouth to lie directly behind the heart. The closer a structure is to the transducer, the better the ultrasound image that can be obtained. In TEE, which heart valve can be best visualized?

A. TricuspidB. PulmonaryC. MitralD. AorticE. Valve of the inferior vena cava

Two days after the patient’s breathing had become assisted by mechanical ventilation, a patient with Guillain-Barré syndrome began experiencing severe cardiac arrhythmia, with perilously slow cardiac contractions, resulting in reduced cardiac output. This most likely resulted from interruption of the contractile stimulus carried by which of the following?A. Left vagus nerveB. Right phrenic nerveC. Preganglionic sympathetic fibers in upper thoracic spinal nervesD. Cardiac pain fibers carried by upper thoracic spinal nervesE. Ventral

A 34-year-old patient had been diagnosed earlier in the week with Guillain-Barré syndrome. He is now in extreme respiratory distress. His thoracic wall contracts and relaxes violently, but there is little movement of the abdominal wall. The degenerative disease has obviously affected the muscle that is most responsible for increasing the vertical dimensions of the thoracic cavity (and pleural cavities). Which of the following is the most likely cause of his disease?A. Paralysis of his intercostal muscles and loss of the “bucket handle movement” of his ribsB. Generalized intercostal nerve paralysis that resulted in loss of the “pump handle movement” of his ribsC. Paralysis of his medial and lateral pectoral nerves, interrupting the function of his pectoralis major muscles, an important accessory muscle of respirationD. Paralysis of his sternocleidomastoid musclesE. Degeneration of the myelin of his phrenic nerves

A 27-year-old male billiards player received a small caliber bullet wound to the chest in the region of the third intercostal space, several centimeters to the left of the sternum. The patient is admitted to the emergency department and a preliminary notation of “Beck’s triad” is entered on the patient’s chart. Which of the following are features of this triad?A. There was injury to the left pulmonary artery, left primary bronchus, and esophagus.B. The patient has bleeding into the pleural cavity, a collapsed lung, and mediastinal shift to the right side of the thorax.C. The patient has a small, quiet heart; decreased pulse pressure; and increased central venous pressure.D. The young man is suffering from marked diastolic emptying, dyspnea, and dilation of the aortic arch.E. The left lung has collapsed, there is paradoxical respiration, and there is a mediastinal shift of the heart and trachea to the left.

A 47-year-old female patient’s right breast exhibited peau d’orange characteristics. This condition is primarily a result of which of the following occurrences?A. Blockage of cutaneous lymphatic vesselsB. Shortening of the suspensory ligaments by cancer in the axillary tail of the breastC. Contraction of the retinacula cutis of the areola and nippleD. Invasion of the pectoralis major by metastatic cancerE. Ipsilateral (same side) inversion of the nipple from cancer of the duct system of the breast

A 3-year-old male who fell from a tree complains of severe pain over the right side of his chest because of a rib fracture at the midaxillary line. He is admitted to the hospital due to his difficulty breathing. Radiographic and physical examinations reveal atelectasis, resulting from the accumulation of blood in his pleural space and resulting hemothorax. What is the most likely the source of bleeding to cause the hemothorax?A. Left common carotid arteryB. Intercostal vesselsC. Pulmonary arteriesD. Pulmonary veinsE. Internal thoracic artery

A 29-year-old patient complains of severe pain radiating across her back and chest. Upon clinical examination you observe a rash characteristic of herpes zoster infection passing from her upper left back and across her left nipple. Which of the following spinal nerveroots sheds the active virus?A. Dorsal root of T3B. Ventral root of T3C. Dorsal root of T4D. Ventral root of T4

A 35-year-old female who was brought into the emergency department for a drug overdose requires insertion of a nasogastric tube and administration of activated charcoal. What are the three sites in the esophagus where one should anticipate resistance due to compression on the organ?A. At the aortic arch, the cricopharyngeal constriction, and the diaphragmatic constrictionB. The cardiac constriction, the cricoid cartilage constriction, and the thoracic ductC. The pulmonary constriction, cricothyroid constriction, and the azygos archD. The cardiac constriction, the azygos arch, the pulmonary trunkE. The cricopharyngeal constriction,

Radiographic examination of a cyanotic 3-day-old infant gives evidence of abnormalities within the heart. Blood tests reveal abnormally high levels of TGF-β factor Nodal. Which of the following conditions is most likely to be associated with these findings?A. DextrocardiaB. Ectopia cordisC. Transposition of the great arteriesD. Unequal division of the truncus arteriosusE. Coarctation of the aorta

A 22-year-old marathon runner is admitted to the emergency department with severe dyspnea. Physical examination reveals that the patient is experiencing anacute asthma attack, and a bronchodilating drug is administered. Which of the following elements of the nervous system must be inhibited by the drug to achieve relaxation of the smooth muscle of the tracheobronchial tree?A. Postganglionic sympathetic fibersB. Preganglionic sympathetic fibersC. Postganglionic parasympathetic fibersD. Visceral afferent fibersE. Somatic efferent fibers

A 62-year-old female accountant is admitted to the emergency department with severe chest pains that radiate to her left arm. ECG reveals that the patient suffers from an acute myocardial infarction. Coronary angiography is performed and a stent is placed at the proximal portion of the anterior interventricular artery (left anterior descending). Because of the low ejection fraction of the right and left ventricles, a cardiac pacemaker is also placed in the heart. The function of which of the following structures is essentially replaced by the insertion of a pacemaker?A. AV nodeB. SA nodeC. Purkinje fibersD. Bundle of HisE. Bundle of Kent

A 62-year-old female is admitted to the hospital with severe dyspnea and also complains of pain over her left shoulder. A radiographic examination reveals an aneurysm of the aortic arch. Which of the following nerves is most likely affected by the aneurysm?A. PhrenicB. VagusC. CardiopulmonaryD. IntercostalE. Thoracic splanchnic

A 57-year-old male is admitted to the emergency department after he was struck by a truck while crossing a busy street. Radiographic examination reveals flail chest. During physical examination the patient complains of severe pain during inspiration and expiration. Which of the following nerves is most likely responsible for the sensation of pain during respiration?A. PhrenicB. VagusC. CardiopulmonaryD. IntercostalE. Thoracic splanchnic

A 35-year-old female is admitted to the hospital with dyspnea. During physical examination her S1 heart sound is very loud. Which of the following valves is/are responsible for production of the S1 heart sound?A. Mitral valveB. Pulmonary and aorticC. Aortic and mitralD. TricuspidE. Tricuspid and mitral

A 35-year-old woman is admitted to the hospital with a complaint of shortness of breath. During physical examination it is noted that there is wide splitting in her S2 heart sound. Which of the following valves is/are responsible for production of the S2 heart sound?A. Mitral valveB. Pulmonary and aorticC. Aortic and mitralD. TricuspidE. Tricuspid and aortic

A 42-year-old woman is admitted to the emergency department after a fall from the balcony of her apartment. During physical examination there is an absence of heart sounds, reduced systolic pressure, reduced cardiac output, and engorged jugular veins. Which condition is most likely characterized by these signs?A. HemothoraxB. Cardiac tamponadeC. HemopneumothoraxD. PneumothoraxE. Deep vein thrombosis

A 34-year-old male with a complaint of sharp, localized pain over the thoracic wall is diagnosed with pleural effusion. A chest tube is inserted to drain the effusion through an intercostal space. At which of the following locations is the chest tube most likely to be inserted?A. Superior to the upper border of the ribB. Inferior to the lower border of the ribC. At the middle of the intercostal spaceD. Between the internal and external intercostal musclesE. Between the intercostal muscles and the posterior intercostal membrane

A 15-year-old male is admitted to the hospital with cough and severe dyspnea. Physical examination reveals expiratory wheezes, and a diagnosis is made of acute asthma. The expiratory wheezes are characteristic signs of bronchospasm of the smooth muscle of the bronchial airways. Which of the following nerves could be blocked to result in relaxation of the smooth muscle?A. PhrenicB. IntercostalC. VagusD. T1 to T4 sympathetic fibersE. Recurrent laryngeal nerve

A 55-year-old woman is admitted to the hospital with cough and severe dyspnea. Radiographic examination reveals that the patient suffers from emphysema. Upon physical examination the patient shows only “bucket handle movements” during deep inspiration. Which of the following movements of the thoracic wall is characteristic for this typeof breathing?A. Increase of the transverse diameter of the thoraxB. Increase of the anteroposterior diameter of the thoraxC. Increase of the vertical dimension of the thoraxD. Decrease of the anteroposterior diameter of the thoraxE. Decrease of the transverse diameter of the thorax

A 45-year-old man is admitted to the hospital with severe chest pain radiating to his left arm and left upper jaw. An emergency ECG reveals an acute myocardial infarction of the posterior left ventricular wall. Which of the following spinal cord segments would most likely receivethe sensations of pain in this case?A. T1, T2, T3B. T1, T2, T3, T4C. T1, T2D. T4, T5, T6E. T5, T6, T7

A 35-year-old man is admitted to the hospital with severe chest pain, dyspnea, tachycardia, cough, and fever. Radiographic examination reveals significant pericardial effusion. When pericardiocentesis is performed, the needle is inserted up from the infrasternal angle. The needle passes too deeply, piercing the visceral pericardium and entering the heart. Which of the following chambers would be the first to be penetrated by the needle?A. Right ventricleB. Left ventricleC. Right atriumD. Left atriumE. The left cardiac apex

A 17-year-old girl is admitted to the hospital with dyspnea and fever. Radiographic examination reveals lobar pneumonia in one of the lobes of her right lung. During stethoscope examination at the level of the sixth intercostal space at the midaxillary line, rales (or crackles) are heard and dull sounds are produced during percussion. Which of the following lobes is most likely to be involved by pneumonia?A. Upper lobe of the right lungB. Middle lobe of the right lungC. Lower lobe of the right lungD. Lower lobes of the right and left lungsE. Upper lobes of the right and left lungs

A 28-year-old woman in the third trimester of pregnancy has experienced severe dizziness for several days and is admitted to the hospital. During physical examination her blood pressure is normal when standing or sitting. When the patient is supine, her blood pressure drops to 90/50 mm Hg. What is the most likely explanation for these findings?A. Compression of the inferior vena cavaB. Compression of the superior vena cavaC. Compression of the aortaD. Compression of the common carotid arteryE. Compression of the internal jugular veins

A 34-year-old male unconscious patient is admitted to the hospital. His blood pressure is 85/45 mm Hg. A central venous line is ordered to be placed. During subsequent radiographic examination a chylothorax is detected. Which of the following structures was most likely accidentally damaged during the placement of the central venous line?A. Left external jugular veinB. Site of origin of the left brachiocephalic veinC. Right subclavian veinD. Proximal part of right brachiocephalic veinE. Right external jugular vein

A 21-year-old female gymnast is admitted to the hospital with severe dyspnea after a fall from the uneven parallel bars. Radiographic examination reveals that her right lung is collapsed and the left lung is compressed by the great volume of air in her right pleural cavity. During physical examination she has no signs of external injuries. Which of the following conditions will most likely describe this case?A. Flail chest with paradoxical respirationB. EmphysemaC. HemothoraxD. ChylothoraxE. Tension pneumothorax

A 42-year-old male is diagnosed with liver and pancreatic disease as a result of alcoholism. During physical examination it is noted that he has abnormal enlargement of his mammary glands, as a secondary result of his disease process. Which of the following clinical conditions will most likely describe this case?A. PolytheliaB. Supernumerary breastC. PolymastiaD. GynecomastiaE. Amastia

A 33-year-old male is admitted to the hospital after a violent, multiple car collision. His blood pressure is 89/39 mm Hg, and a central venous line is ordered to be placed. Which of the following structures is used as a landmark to place the tip of the catheter of the central venous line?A. CarinaB. Subclavian arteryC. Superior vena cavaD. Left atriumE. Right atrium

A 47-year-old woman is admitted to the hospital with pain in her neck. During physical examination it is observed that the thyroid gland is enlarged and is compressing the trachea. A biopsy reveals a benign tumor. A CT scan examination reveals tracheal deviation to the left. Which of the following structures will most likely be compressed as a result of the deviation?A. Left brachiocephalic veinB. Left internal jugular veinC. Left subclavian arteryD. Vagus nerveE. Phrenic nerve

A 60-year-old man is admitted to the hospital with severe abdominal pain. A CT scan reveals a dissecting aneurysm of the thoracic aorta. While in the hospital the patient’s aneurysm ruptures and he is transferred urgently to the operating theater. Postoperatively, the patient suffers from paraplegia. Which of the following arteries was most likely injured during the operation to result in the paralysis?A. Right coronary arteryB. Left common carotidC. Right subclavianD. Great radicular (of Adamkiewicz)E. Esophageal

A 42-year-old man is admitted to the hospital with retrosternal pain. Endoscopy and biopsy examinations of the trachea reveal a malignant growth at the right main bronchus. Which of the following lymph nodes will most likely be the first infiltrated by cancerous cells from the malignancy?A. Inferior tracheobronchialB. ParatrachealC. Bronchomediastinal trunkD. BronchopulmonaryE. Thoracic duct

A 39-year-old man is admitted to the hospital with odynophagia. A barium swallow reveals an esophageal constriction at the level of the diaphragm. A CT scan and a biopsy further indicate the presence of an esophageal cancer. Which of the following lymph nodes will most likely be affected first?A. Posterior mediastinal and left gastricB. BronchopulmonaryC. TracheobronchialD. Inferior tracheobronchialE. Superior tracheobronchial

A 33-year-old male is admitted to the hospital with severe traumatic injuries. His blood pressure is 89/39 mm Hg, and a central venous line is ordered to be placed. Which of the following injuries is most likely to occur when a subclavian central venous line procedure is performed?A. Penetration of the subclavian arteryB. Impalement of the phrenic nerveC. Penetration of the superior vena cavaD. Penetration of the left common carotid arteryE. Impalement of the vagus nerve

A 25-year-old female is admitted to the hospital after a violent automobile crash. Radiographic examination reveals four broken ribs in the left thoracic wall, producing a flail chest observable on physical examination. Which of the following conditions is most likely to also be observed during physical examination?A. During deep inspiration the flail segment moves in the opposite direction of the chest wall.B. During deep inspiration the flail segment moves in the same direction as the chest wall.C. “Pump handle movements” of the ribs will not be affected by the rib fractures.D. The descent of the diaphragm will be affected on the side of the broken ribs.E. The descent of the diaphragm will be affected on the side of the broken ribs and also on the opposite side.

A 42-year-old woman is seen by her family physician because she has a painful lump in her right breast and a bloody discharge from her right nipple. Upon physical examination it is noted that there is unilateral inversion of the right nipple and a hard, woody texture of the skin over a mass of tissue in the right upper quadrant of the breast. Which of the following conditions is most frequentlycharacterized by these symptoms?A. Peau d’orangeB. Cancer en cuirasseC. Intraductal cancerous tumorD. Obstruction of the lymphatics draining the skin of the breast, with edema of the skinE. Inflammation of the epithelial lining of the nipple and underlying hypodermis

A 51-year-old female with a history of brain tumor and associated severe oropharyngeal dysphagia develops right lower lobe pneumonia after an episode of vomiting. Which of the following is the best reason that this type of aspiration pneumonia most commonly affects the right lower lung lobe?A. Pulmonary vascular resistance is higher in the right lung than the left lung.B. The right main bronchus is straighter than the left main bronchus.C. The right main bronchus is narrower than the main bronchus.D. The right main bronchus is longer than the left main bronchus.E. The right lower lung lobe has poorer venous drainage than the other lobes.

A 25-year-old man is admitted to the emergency department with a bullet wound in the neck just above the middle of the right clavicle and first rib. Radiographic examination reveals collapse of the right lung and a tension pneumothorax. Injury to which of the following respiratory structures resulted in the pneumothorax?A. Costal pleuraB. CupulaC. Right mainstem bronchusD. Right upper lobe bronchusE. Mediastinal parietal pleura

A 10-year-old boy is admitted to the hospital with retrosternal discomfort. A CT scan reveals a midline tumor of the thymus gland. Which of the following veins would most likely be compressed by the tumor?A. Right internal jugularB. Left internal jugularC. Right brachiocephalicD. Left brachiocephalicE. Right subclavian

In coronary bypass graft surgery of a 49-year-old female, the internal thoracic artery is used as the coronary artery bypass graft. The anterior intercostal arteries in intercostal spaces three to six are ligated. Which of the following arteries will be expected to supply these intercostal spaces?A. MusculophrenicB. Superior epigastricC. Posterior intercostalD. Lateral thoracicE. Thoracodorsal

A 47-year-old male is admitted to the emergency department, due to severe dysphagia. Edema of the lower limbs is apparent upon physical examination. A barium sulfate swallow imaging procedure reveals esophageal dilation, with severe inflammation, due to constriction at the esophageal hiatus. What is the most likely cause of the severe edema of the lower limbs?A. Thoracic aorta constrictionB. Thoracic duct blockageC. Superior vena caval occlusionD. Aortic aneurysmE. Femoral artery disease

A 22-year-old woman sustained a chest injury upon impact with the steering wheel during a car crash. Upon admission of the patient to the hospital, physical examination revealed profuse swelling, inflammation, and deformation of the chest wall. A radiograph revealed an uncommon fracture of the manubrium at the sternomanubrial joint. Which of the following ribs would be most likely to also be involved in such an injury?A. FirstB. SecondC. ThirdD. FourthE. Fifth

A 22-year-old man is diagnosed with signs of reduced aortic flow. Upon examination it is noted that brachial artery pressure is markedly increased, femoral pressure is decreased, and the femoral pulses are delayed. The patient shows no external signs of inflammation. Which ofthe following conditions will most likely be observed in a radiographic examination?A. Flail chestB. PneumothoraxC. HydrothoraxD. Notching of the ribsE. Mediastinal shift

A 30-year-old man is admitted to the emergency department because of significant nose bleeding and a headache that has worsened over several days. He also complains of fatigue. Upon examination it is noted that brachial artery pressure is markedly increased, femoral pressure is decreased, and the femoral pulses are delayed. The patient shows no external signs of inflammation. Which of the following is the most likelydiagnosis?A. Coarctation of the aortaB. Cor pulmonaleC. Dissecting aneurysm of the right common iliac arteryD. Obstruction of the superior vena cavaE. Pulmonary embolism

A 35-year-old woman is admitted to a surgical ward with a palpable mass in her right breast and swollen lymph nodes in the axilla. Radiographic studies and biopsy reveal carcinoma of the breast. Which group of axillary lymph nodes is the first to receive lymph drainage from the secretory tissue of the breast and therefore most likely to contain metastasized tumor cells?A. LateralB. CentralC. ApicalD. Anterior (pectoral)E. Posterior (subscapular)

A 72-year-old patient vomited and then aspirated some of the vomitus while under anesthesia. On bronchoscopic examination, partially digested food is observed blocking the origin of the right superior lobar bronchus. Which of the following groups of bronchopulmonary segments will be affected by this obstruction?A. Superior, medial, lateral, medial basalB. Apical, anterior, posteriorC. Posterior, anterior, superior, lateralD. Apical, lateral, medial, lateral basalE. Anterior, superior, medial, lateral

A 58-year-old woman is admitted to the emergency department with severe dyspnea. Bronchoscopy reveals that the carina is distorted and widened. Enlargement of which group of lymph nodes is most likely responsible for altering the carina?A. PulmonaryB. BronchopulmonaryC. Inferior tracheobronchialD. Superior tracheobronchialE. Paratracheal

A 55-year-old female visited her doctor because of a painful lump in her right breast and a bloody discharge from her right nipple. Radiographic studies and physical examination reveal unilateral inversion of the nipple, and a tumor in the right upper quadrant of the breast is suspected. In addition, there is an orange-peel appearance of the skin (peau d’orange) in the vicinity of the areola. Which of the following best explains the inversion of her nipple?A. Retention of the fetal and infantile state of the nippleB. Intraductal cancerous tumorC. Retraction of the suspensory ligaments of the breast by cancerD. Obstruction of the cutaneous lymphatics, with edema of the skinE. Inflammation of the epithelial lining of the nipple and underlying hypodermis

A 54-year-old female is admitted to the hospital with a stab wound of the thoracic wall in the area of the right fourth costal cartilage. Which of the following pulmonary structures is present at this site?A. The horizontal fissure of the left lungB. The horizontal fissure of the right lungC. The oblique fissure of the left lungD. The apex of the right lungE. The root of the left lung

A 3-year-old child is admitted to the emergency department with a particularly severe attack of asthma. Which of the following is the most important factor in increasing the intrathoracic capacity in inspiration?A. “Pump handle movement” of the ribs—thereby increasing anterior-posterior dimensions of the thoraxB. “Bucket handle movement” of the ribs— increasing the transverse diameter of the thoraxC. Straightening of the forward curvature of the thoracic spine, thereby increasing the vertical dimensions of the thoracic cavityD. Descent of the diaphragm, with protrusion of the abdominal wall, thereby increasing vertical dimensions of the thoracic cavityE. Orientation and flexibility of the ribs in the baby, thus allowing expansion in all directions

A 5-year-old boy had been playing with his little race cars. Soon after he put a wheel from one of the cars in his mouth, he began choking and coughing. Where in the tracheobronchial tree is the most common site for a foreign object to lodge?A. The right primary bronchusB. The left primary bronchusC. The carina of the tracheaD. The beginning of the tracheaE. The left tertiary bronchus

A 51-year-old male is admitted to the hospital with severe dyspnea. Radiographic examination reveals a tension pneumothorax. Adequate local anesthesia of the chest wall prior to insertion of a chest tube is necessary for pain control. Of the following layers, which is the deepest that must be infiltrated with the local anesthetic to achieve adequate anesthesia?A. Endothoracic fasciaB. Intercostal musclesC. Parietal pleuraD. Subcutaneous fatE. Visceral pleura

ANSWERS: THORAX

C. The mitral valve is best visualized by TEE because the transducer within the esophagus is directly posterior to the left atrium. The physical laws that apply to ultrasound imaging dictate that the closer the structure to the transducer, the better the ability to obtain a better image. This question asks which heart valve is most directly related to the posterior aspect of the left atrium, which is the mitral valve.

C. The lost of myelin from the preganglionic (normally myelinated) sympathetic fibers in T1 to T4 results in interruption in their transmission of electrical stimulating impulses and, therefore, reduction of positive inotropic (force increasing) and chronotropic (rate increasing) stimulation of the heart. Reduction of function of the vagus nerves would not result in slowing cardiac activity; just the opposite would occur. Interruption of phrenic nerve activity has no effect on cardiac rate (as this nerve innervates the diaphragm), nor would the interruption of the thinly myelinated pain fibers from the heart. The ventral horn neurons do not innervate the heart, but rather skeletal muscle; therefore, they would not be directly affected by the disease process affecting the heart.

E. Myelin degeneration of the phrenic nerves, as can occur in Guillain-Barré, results in loss of phrenic nerve function and paralysis of the diaphragm. Diaphragmatic paralysis is predictable with lack of movement of the abdominal wall in respiratory efforts. The ribs are moving “violently” in this case; therefore, intercostal muscles and the pectoral musculature have retained their motor supply.

C. The patient is suffering from cardiac tamponade, that is, filling of the pericardial cavity with fluid. The classic signs of this tamponade are referred to as “Beck’s triad.” This trio, by definition, includes a small heart, from compression of the heart by the fluid-filled pericardial sac,and a quiet heart because the tamponade muffles the cardiac sounds; decreased pulse pressure resulting from the reduced difference between systolic and diastolic pressure because the tamponade restricts the ability of the heart to fill in diastole; and increased central venous pressure because venous blood cannot enter the compressed heart. None of the other answers provided includes these data to fit the definition.

A. Blockage of cutaneous lymphatic vessels results in edema of the skin surrounding the hair follicles, leading to an appearance like an orange peel (peau d’orange). Shortening of the suspensory ligaments leads to dimpling of the overlying skin, not peau d’orange. Contraction of retinacula cutis results in retraction and inversion of the nipple and/or areola. Pectoralis major involvement has nothing to do with this condition but can result in fixing the tumor firmly to the chest wall.

B. Due to rib fracture, the intercostal vessels are damaged, parietal pleura is torn, and blood flows into the pleural space. The loss of negative pressure within the pleural cavity results in collapse of the lung. The carotid vessels would not be affected by the described injury. The pulmonary vessels are found within the parenchyma of the lungs and would not be injured due to an external injury such as that described. The internal thoracic artery is well protected by the sternum and is not the cause of this hemothorax.

C. The dermatome that encompasses the nipple is supplied by spinal nerve T4. In this case the herpes zoster virus is harbored in the dorsal root ganglion of T4 and can be activated to cause the characteristic rash that is distributed along the dermatome including the nipple.

A. The esophagus typically has four constrictions. In the thorax the esophagus is compressed by (1) the arch of the aorta, (2) the left principal bronchus, and (3) the diaphragm. The cricopharyngeal constriction is in the neck.

A. Dextrocardia is a condition that results from a bending of the heart tube to the left instead of to the right. TGF-β factor Nodal plays a role in the looping of the heart during the embryonic period.

C. Postganglionic parasympathetic fibers are involved in the constriction of smooth muscle in the tracheoesophageal tree. Sympathetic fibers cause dilation of this structure. Visceral and somatic afferents are sensory fibers and therefore cannot cause dilation of muscle, as this is a motor nerve function.

B. The SA node functions as the primary intrinsic pacemaker of the heart, setting the cardiac rhythm. An artificial pacemaker assists in producing a normal rhythm when the SA node is not functioning normally. The atrioventricular node receives the depolarization signals from the sinoatrial node. The signal is delayed within the atrioventricular node (providing the time for the atria to contract), then propagated from the atrioventricular node through the bundle of His and Purkinje fibers.

A. An aneurysm of the aortic arch could impinge upon the phrenic nerve, causing referral of pain to the left shoulder. This referral occurs because the root levels of the phrenic nerve are C3 to C5, nerve levels that are also distributed to the skin over the shoulder region. The other choices do not cause referral of pain to the left shoulder. The vagus nerve does not transmit pain sensations except from certain organs in the abdomen and pelvis. The intercostal nerves carry sensory information from the intercostal spaces and parietal pleura, pain that would not be referred to the shoulder. The thoracic splanchnics carry sympathetic innervation to the abdomen.

D. Flail chest is characterized by paradoxical breathing movements caused by multiple rib fractures. The sensory innervation provided to intercostal spaces and to the underlying parietal pleura is supplied via the corresponding intercostal nerves. The phrenic nerve provides motor innervation to the diaphragm and sensory innervation to the diaphragmatic and mediastinal parietal pleura and pericardium. The vagus nerves provide parasympathetic innervation to the thoracic viscera, and to the gastrointestinal tract as distal as the left colic flexure. The cardiopulmonary nerves carry sympathetic innervation from T1 to T4 levels to the thoracic organs, and pain fibers from these organs. Thoracic splanchnic nerves carry sympathetic innervation to the abdomen.

E. The closure of the mitral/bicuspid and tricuspid valves produces the first S1(lub) heart sound. The S2 heart sound refers to the second (dub) heart sound. This latter sound is produced by the closure of the aortic and pulmonary semilunar valves.

B. The S2 heart sound refers to the second (dub) heart sound. This sound is produced by the closure of the aortic and pulmonary semilunar valves. The closure of mitral/bicuspid and tricuspid valves produce the first S1(lub) heart sound.

B. Cardiac tamponade is a condition in which fluid accumulates in the pericardial cavity. It can result from pericardial effusion or from leakage of blood from the heart or proximal portions of the great vessels. The increased pressure within the pericardial sac leads to decreased cardiac filling during diastole and therefore reduced systolic blood pressure. Because of the reduced pumping capacity of the heart, there is increased pressure in the venous system, leading to the distension of the jugular venous system. Deep vein thrombosis often occurs in the lower limbs and increases the risk of pulmonary embolism. The other answers listed are conditions that affect pulmonary function rather than cardiac functions.

A. The location where one is least likely to damage important structures by making an incision or pushing a chest tube into the thorax is over the upper border of the rib. At the inferior border of each rib, one will encounter intercostal vein, artery, and nerve, in that order (VAN structures). Entrance through the middle of the intercostal space does not eliminate the heightened possibility of piercing important structures. Neither passage between the internal and external intercostal muscles, nor between the intercostal muscles and the posterior intercostal membrane would allow entry to the pleural cavity.

C. Bronchial constriction is induced by the parasympathetic innervation of the airways. This is supplied by the vagus nerves, which could be blocked to result in relaxation of the airways. The phrenic nerve provides motor and sensory innervation to the diaphragm. The intercostal nerves provide sensory and somatic motor innervation to their respective intercostal spaces. Stimulation of sympathetic innervation results in bronchodilation. The recurrent laryngeal nerve is a branch of the vagus and innervates parts of the larynx.

A. The “bucket handle movement” of the ribs affects the transverse diameter of the thorax. Inspiration would increase the transverse diameter, whereas expiration decreases the transverse diameter. The anteroposterior diameter of the thorax is increased and decreased by the “pump handle movements” of the ribs and sternum. Vertical dimensions of the thorax would be changed by contraction and relaxation of the diaphragm.

B. The pain experienced by the patient travels with the sympathetic innervation of the heart, derived from spinal nerve levels T1 to T4. The pain fibers leave the heart and the cardiac plexuses via the cardiopulmonary nerves. Subsequently, the pain fibers pass through the sympathetic chain, enter the spinal nerve, and pass into the dorsal roots of the spinal nerves. The cell bodies of the pain fibers are located in the dorsal root ganglia of the spinal nerves from T1 to T4. The other levels indicated do not correspond to the typical pattern of innervation of this region.

A. Pericardiocentesis is usually performed through the infrasternal angle with the needle passing up through the diaphragm to the fibrous pericardium. The diaphragmatic surface of the heart is largely composed of the right ventricle and would therefore be entered if a needle is inserted too far. The other chambers of the heart would not lie in the direct path of the needle.

C. Crackling noises in the lungs due to the buildup of fluid are referred to as rales. The fluid usually migrates to the inferior portion of the lung due to the effects of gravity. Auscultation over the sixth intercostal space at the midaxillary line would be associated with the lower lobe of the right lung. Remember that the oblique fissure runs from the level of T2 posteriorly to the sixth costal cartilage anteriorly. At the sixth intercostal space in the midaxillary line, one would be percussing below this fissure and therefore over the lower lobe. This question does not indicate any examination of the left lung.

A. The inferior vena cava quite likely undergoes compression by the growing fetus when the mother is in the supine position. In this case the compression led to reduced blood flow through the heart, with a resultant drop in blood pressure. The other structures listed as answers are not likely to be compressed by the growing fetus.

B. Chylothorax is usually caused by injury to the thoracic duct. The thoracic duct enters the venous system at the junction of the left internal jugular vein and the left subclavian vein, where they form the left brachiocephalic vein. Penetrating injuries at the beginning of the left brachiocephalic vein commonly also disrupt the termination of the thoracic duct. The other answers provided do not receive lymphatic drainage from the thoracic duct.

E. A tension pneumothorax is caused by injury to the lung, leading to air in the pleural cavity. The site of the wound acts as a one-way valve, allowing air to enter the pleural cavity but not to leave the cavity. The lack of negative pressure in the pleural cavity causes the lung to collapse. Neither flail chest, emphysema, nor hemothorax will necessarily lead to the increased volume of air in the pleural cavity. The tension pneumothorax occurred during a violent fall; therefore, the clinical condition is not likely to be a spontaneous pneumothorax, in which case there is rupture of the pleura without the necessary occurrence of trauma.

D. Gynecomastia is the abnormal growth of mammary glands in males. Polythelia refers to supernumerary nipples. Polymastia refers to supernumerary, or extra, breasts. Amastia refers to the absence of breasts.

A. The carina is the only answer listed that can easily be seen in radiograph. The carina is at the level of T4-5 (plane associated with the sternal angle of Louis). This landmark is commonly used to guide the placement of a central venous line.

A. A left tracheal deviation with an enlarged thyroid gland will most likely compress the left brachiocephalic vein. The other answer choices lie too far laterally to be affected by the tracheal deviation.

D. The artery of Adamkiewicz (great radicular artery) is an important artery that provides oxygenated blood to the lower portion of the spinal cord, specifically the anterior cord where lower motor neurons are located, inferior to the vertebral level of origin of the artery, and provides collateral anastomoses with the anterior spinal artery. Care should be taken during surgery to prevent damage to this artery as this can lead to paraplegia and alteration of functions of pelvic organs. The other answer choices are not likely to be damaged during the surgery and would not lead to paraplegia.

A. Lymph from the right primary bronchus would drain first into the inferior tracheobronchial nodes. The bronchomediastinal trunk and the thoracic duct are not lymph nodes, so they cannot be the correct answers to the question. The paratracheal nodes receive lymph from the superior tracheobronchial nodes. The superior tracheobronchial nodes receive lymph from the inferior tracheobronchial nodes.

A. Lymph from the lower third of the esophagus drains into the posterior mediastinal and left gastric lymph nodes. The middle third of the esophagus drains into posterior and superior mediastinal lymph nodes. The upper third of the esophagus drains into the deep cervical nodes. The other answer choices drain parts of the trachea, bronchi, and lungs.

A. The subclavian artery lies directly posterior to the subclavian vein; therefore, it is the structure that would be most vulnerable to damage when placing a central venous line in the subclavian vein. Both the phrenic and vagus nerves will be medial to the placement of the line and are not likely to be damaged. The common carotid artery is also too medial to be damaged by the line. The superior vena cava lies medial and inferior to the site of placement and is too deep to be easily damaged.

A. When multiple rib fractures produce a flail segment of the thoracic wall, paradoxical motion of the flail segment is commonly experienced upon deep inspiration; that is, the flail area is sucked in rather than expanding outward with inspiration, and the reverse movement occurs in expiration. Because the ribs are fractured, they will not be able to facilitate the normal “pump handle” motion during inspiration. The excursions of the diaphragm will not be affected by the broken ribs, except as pain restricts the breathing effort of the patient.

B. All of the symptoms described in the question are indicative of breast cancer. The best choice of answers is cancer en cuirasse, a pathologic condition that presents as a hard, “woodlike” texture. Intraductal cancerous tumor is often a mild form of cancer detected by mammography. A, D, and E are all symptoms, not pathologic conditions.

B. The right primary bronchus is shorter, wider, and more vertical than the left main bronchus. When a foreign body is aspirated, it is more likely to enter the right main bronchus (although in some cases the foreign body enters the left bronchus). Pulmonary vascular resistance is not related to the question. The right lower lung lobe does not have poorer venous drainage than the other lobes.

B. The parietal pleura can be divided regionally into costal, diaphragmatic, mediastinal, and cervical portions, depending upon local topographic relations. Another name for the cervical pleura is the cupula. This forms the dome of the plura, projecting into the neck above the first rib and corresponding to the area of injury. The costal pleura lines the internal surfaces of the ribs and intercostal spaces. The mediastinal pleura lies between the lungs and the organs in the mediastinum. The right primary bronchus and upper lobe bronchus are not in the vicinity of the right clavicle or first rib.

D. The thymus lies in the superior mediastinum and extends upward into the neck, especially in the young. A midline tumor of this gland can compress the left brachiocephalic vein. The subclavian vein is distal or lateral to this location, and the thymus gland would not likely impinge upon it. The internal jugular veins are located superior and lateral to the position of the thymus gland. A midline tumor is more likely to cause compression of the left brachiocephalic vein, which crosses the midline, than the right brachiocephalic vein, which is not located in the midline.

C. The anterior intercostal arteries anastomose with the posterior intercostal arteries. Ligation of the anterior arteries would not affect the supply of the intercostal spaces because the posterior arteries would provide collateral arterial supply. Branches of the musculophrenic artery provide supply for the lower seventh, eighth, and ninth intercostal spaces. The superior epigastric artery passes into the rectus sheath of the anterior abdominal wall. The lateral thoracic artery arises from the second part of the axillary artery, and the thoracodorsal artery is a branch of the subscapular artery, a branch of the third part of the axillary artery.

B. The thoracic duct is important in lymph drainage of the entire body with the exception of the upper right quadrant. The thoracic duct ascends between the aorta and azygos vein behind the esophagus. Dilation of the esophagus here in the lower thorax can compress the thoracic duct, leading to impairment of lymphatic drainage and resultant edema.

B. The superior margin of the manubrium is characterized by the jugular notch. Laterally are the sternoclavicular joints and the articulations of the first ribs with the manubrium. The second pair of ribs articulates with the sternum at the sternal angle, the junction of the manubrium with the body of the sternum.

D. The diagnosis for these symptoms is coarctation of the aorta. This condition occurs when the aorta is abnormally constricted. One of the cardinal signs is a characteristic rib notching. “Notching” of the ribs is due to the reversal of direction of blood flow through the anterior intercostal branches of the internal thoracic artery, as these usually small arteries carry collateral arterial blood flow to the lower thoracic portion of the aorta inferior to the coarctation. Enlargement and vibration of the intercostal arteries against the rib results in erosion (“notching”) of the subcostal grooves, which is visible on radiography.

A. Increased arterial pressure in the upper limbs (as demonstrated in the brachial artery) and decreased pressure in the lower limbs (as demonstrated in the femoral artery) are common symptoms of coarctation of the aorta. Other symptoms include tortuous and enlarged blood vessels above the coarctation and an increased risk ofcerebral hemorrhage. This condition of coarctation occurs when the aorta is abnormally constricted during development. The patient does not complain of respiratory distress, so cor pulmonale would not likely be the underlying condition. Dissection of the right common iliac artery would not result in nosebleed or headache. Obstruction of the superior vena cava would not account for decreased femoral pulse. A pulmonary embolism will not present with these findings.

D. Lymphatic drainage of the breast is typically to the axillary nodes, more specifically to the anterior (pectoral) nodes. Lymphatic vessels from the pectoral nodes continue into the central axillary nodes, the drainage of which passes farther into the apical node, just inferior to the clavicle in the deltopectoral triangle. From these nodes lymph passes to the “sentinel,” or scalene, nodes and the subclavian lymph trunk. The lateral and posterior axillary nodes do not normally receive lymph drainage from the breast but do receive lymph from the upper limb. (This is the reason for the edema of the upper limb that occurs after a mastectomy, in which there may be a total removal of axillary lymph nodes.)

B. The superior lobar bronchus is one of the divisions of the right main bronchus. This bronchus branches into apical, anterior, and posterior tertiary bronchi.

C. The inferior tracheobronchial nodes are also known as the carinal nodes and are located on the inferior aspect of the carina, the site of bifurcation of the trachea. The pulmonary nodes lie on secondary bronchi. The bronchopulmonary (hilar) nodes run along the primary bronchi. The superior tracheobronchial nodes are at the junction of the bronchi and the trachea. The paratracheal nodes run along the trachea.

C. The patient’s symptoms are all indicative of inflammatory breast cancer. Common symptoms include inversion of the nipple and dimpling of the overlying skin, changes that are due to the retraction of the suspensory ligaments (of Cooper). Intraductal cancerous tumors show symptoms including breast enlargement, breast lump, breast pain, and nipple discharge. The other answers are not cancerous conditions.

B. The horizontal fissure of the right lung is a fissure separating the superior lobe from the middle lobe. It usually extends medially from the oblique fissure at the midaxillary line to the sternum, along the lower border of the fourth rib. The apex of the right lung reaches to a level above the clavicle and is therefore superior to the stab wound in the fourth costal cartilage. The other answers are related to features of the left lung, which is not addressed in the question.

D. Contraction of the diaphragm (descent) pulls the dome inferiorly, increasing the vertical dimension of the thorax. This is the most important factor in inspiration for increasing the internal pulmonary volume and concomitantly decreasing intrathoracic pressure. The contraction of intercostal muscles is usually involved in forced inspiration, resulting in increases in the transverse and anteroposterior dimensions of the thoracic cavity.

A. The right main bronchus is the shorter, wider, and more vertical primary bronchus. Therefore, this is most often the location that foreign objects will likely be lodged. The left primary bronchus is not as vertical and therefore does not present the path of least resistance. (It must be understood, however, that in some cases of aspiration, the foreign body can pass into the left primary bronchus rather than the right bronchus!) The carina is a ridge separating the openings of left and right bronchi, the “fork in the road,” so to speak. The trachea is a tubular structure supported by incomplete cartilaginous rings, and the likelihood that an object will be lodged there is minimal. It is unlikely that a foreign object would descend so far as to obstruct a tertiary bronchus, although this could happen.

C. The parietal pleura is innervated by the intercostal nerves and is very sensitive to pain, in this case being somatic innervation. Therefore, the parietal pleura is the deepest layer that must be anesthetized to reduce pain during aspiration or chest tube placement.